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    PLEG is not healthy: Kubernetes Worker Node is in "NotReady" state

    PLEG is not healthy: Kubernetes Worker Node is in "NotReady" state

    The Kubernetes worker node shows "NotReady" state. The Error Shows as follows:

    kubelet: I1014    16235 setters.go:518] Node became not ready: {Type:Ready Status:False LastHeartbeatTime:2019-10-14 01:40:08.225067533 -0500 CDT m=+3261716.350230569 LastTransitionTime:2019-10-14 01:40:08.225067533 -0500 CDT m=+3261716.350230569 Reason:KubeletNotReady Message:PLEG is not healthy: pleg was last seen active 3m5.74712971s ago; threshold is 3m0s}

    When node enters a NotReady state due to an unhealthy PLEG. Check if you can pull all container Information.

     # curl --unix-socket /var/run/docker.sock http://v1.26/containers/json?all=1
    # docker ps
    # docker info

    The PLEG issue can be due to node Overload, so we need to check cpu, memory. it may be due to over scheduled of pods.
    PLEG is a simple loop that does the following:

    1. list pod sandbox containers
    2. list pod containers
    3. wait 1s
    4. return to step 1.

    PLEG is marked unhealthy if the interval for any of these loops exceeds 3 minutes. An unhealthy PLEG marks a node NotReady to defer the scheduler from scheduling additional pods to the node until the machine stabilizes. A NotReady node is still doing work. PLEG returned to normal after the docker daemon stabilized on the system.

    Interesting Articles on Kubernetes:

    Kubernetes : Kubernetes Node Management, Maintenance, Delete
    How to add a  New Worker Node to a existing kubernetes Cluster
    MinIO Client Installation and Quickstart
    PLEG is not healthy: Kubernetes Worker Node is in "NotReady" state
    Backup MySQL databases in Kubernetes
    How to Run Automated Tasks in Kubernetes with a cronjob

    How to Completely remove Kubernetes


    The workaround for this issue is to restart the docker services on the problematic Node.

    systemctl restart docker


    You can reboot the problematic Node.

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